Tweet
Tweet

Slide 1

Slide 1 text

Networking without an OS Josh Triplett [email protected] PyCon 2016

Slide 2

Slide 2 text

No content

Slide 3

Slide 3 text

No content

Slide 4

Slide 4 text

Porting Python to run without an OS

Slide 5

Slide 5 text

PyCon 2015 BIOS Implementation Test Suite (BITS) Python in GRUB and EFI, without an OS Explore and test hardware and firmware

Slide 6

Slide 6 text

No content

Slide 7

Slide 7 text

No content

Slide 8

Slide 8 text

BITS Capabilities Interactive Python interpreter (with line editing and tab completion)

Slide 9

Slide 9 text

BITS Capabilities Interactive Python interpreter (with line editing and tab completion) Direct access to hardware and physical memory

Slide 10

Slide 10 text

BITS Capabilities Interactive Python interpreter (with line editing and tab completion) Direct access to hardware and physical memory Python can call EFI firmware protocols via ctypes

Slide 11

Slide 11 text

BITS Capabilities Interactive Python interpreter (with line editing and tab completion) Direct access to hardware and physical memory Python can call EFI firmware protocols via ctypes Most of the Python standard library

Slide 12

Slide 12 text

Most of the Python standard library

Slide 13

Slide 13 text

Most of the Python standard library Some modules don’t make sense without an OS

Slide 14

Slide 14 text

os.execve os.fork

Slide 15

Slide 15 text

os.execve os.fork multiprocessing popen2 subprocess

Slide 16

Slide 16 text

os.execve os.fork multiprocessing popen2 subprocess webbrowser

Slide 17

Slide 17 text

import antigravity

Slide 18

Slide 18 text

socket select

Slide 19

Slide 19 text

socket select urllib2 httplib SocketServer BaseHTTPServer

Slide 20

Slide 20 text

EFI networking protocols EFI_IP4_CONFIG2_PROTOCOL EFI_TCP4_PROTOCOL

Slide 21

Slide 21 text

Why networking in firmware? Send scripts or test data into the machine

Slide 22

Slide 22 text

Why networking in firmware? Send scripts or test data into the machine Read test data or logs from the machine

Slide 23

Slide 23 text

Why networking in firmware? Send scripts or test data into the machine Read test data or logs from the machine Avoid relying on a writable filesystem

Slide 24

Slide 24 text

Why networking in firmware? Send scripts or test data into the machine Read test data or logs from the machine Avoid relying on a writable filesystem Speed up edit/compile/boot/run cycle

Slide 25

Slide 25 text

Demo

Slide 26

Slide 26 text

Bridging EFI networking and Python sockets Could call EFI network protocols directly Want compatibility with existing Python networking code Python modules import socket and select socket (Python) imports _socket (C)

Slide 27

Slide 27 text

Sockets overview “Berkeley” sockets

Slide 28

Slide 28 text

Sockets overview “Berkeley” sockets Standard on UNIX/POSIX systems, and on Windows via WinSock

Slide 29

Slide 29 text

Sockets overview “Berkeley” sockets Standard on UNIX/POSIX systems, and on Windows via WinSock Focusing exclusively on TCP/IP connections

Slide 30

Slide 30 text

Creating a socket int s = socket(AF_INET, SOCK_STREAM, 0);

Slide 31

Slide 31 text

Creating a socket int s = socket(AF_INET, SOCK_STREAM, 0); AF_INET - IP

Slide 32

Slide 32 text

Creating a socket int s = socket(AF_INET, SOCK_STREAM, 0); AF_INET - IP SOCK_STREAM - TCP

Slide 33

Slide 33 text

Creating a socket int s = socket(AF_INET, SOCK_STREAM, 0); AF_INET - IP SOCK_STREAM - TCP Can use s as either client or server socket

Slide 34

Slide 34 text

Client socket socket

Slide 35

Slide 35 text

Client socket socket connect

Slide 36

Slide 36 text

Client socket socket connect struct sockaddr

Slide 37

Slide 37 text

Client socket socket connect struct sockaddr send/recv

Slide 38

Slide 38 text

Client socket socket connect struct sockaddr send/recv close

Slide 39

Slide 39 text

Server socket socket

Slide 40

Slide 40 text

Server socket socket bind

Slide 41

Slide 41 text

Server socket socket bind struct sockaddr

Slide 42

Slide 42 text

Server socket socket bind struct sockaddr listen

Slide 43

Slide 43 text

Server socket socket bind struct sockaddr listen accept - returns a new connected socket

Slide 44

Slide 44 text

Server socket socket bind struct sockaddr listen accept - returns a new connected socket send/recv

Slide 45

Slide 45 text

Server socket socket bind struct sockaddr listen accept - returns a new connected socket send/recv close

Slide 46

Slide 46 text

select - waiting for activity Pass sets of file descriptors to monitor for reading and for writing

Slide 47

Slide 47 text

select - waiting for activity Pass sets of file descriptors to monitor for reading and for writing And for exceptions, but ignoring that here

Slide 48

Slide 48 text

select - waiting for activity Pass sets of file descriptors to monitor for reading and for writing And for exceptions, but ignoring that here Pass a timeout

Slide 49

Slide 49 text

select - waiting for activity Pass sets of file descriptors to monitor for reading and for writing And for exceptions, but ignoring that here Pass a timeout Waits for a connected socket to have data to recv or send

Slide 50

Slide 50 text

select - waiting for activity Pass sets of file descriptors to monitor for reading and for writing And for exceptions, but ignoring that here Pass a timeout Waits for a connected socket to have data to recv or send Waits for a listening socket to have a connection

Slide 51

Slide 51 text

select - waiting for activity Pass sets of file descriptors to monitor for reading and for writing And for exceptions, but ignoring that here Pass a timeout Waits for a connected socket to have data to recv or send Waits for a listening socket to have a connection Core of the main loop in most network servers

Slide 52

Slide 52 text

select - waiting for activity Pass sets of file descriptors to monitor for reading and for writing And for exceptions, but ignoring that here Pass a timeout Waits for a connected socket to have data to recv or send Waits for a listening socket to have a connection Core of the main loop in most network servers Many OS-specific replacements for scalability and performance

Slide 53

Slide 53 text

Python bindings import socket, select

Slide 54

Slide 54 text

Python bindings import socket, select s = socket.socket() - defaults to TCP/IP

Slide 55

Slide 55 text

Python bindings import socket, select s = socket.socket() - defaults to TCP/IP s.connect

Slide 56

Slide 56 text

Python bindings import socket, select s = socket.socket() - defaults to TCP/IP s.connect s.bind, s.listen, s.accept

Slide 57

Slide 57 text

Python bindings import socket, select s = socket.socket() - defaults to TCP/IP s.connect s.bind, s.listen, s.accept s.sendall, s.recv

Slide 58

Slide 58 text

Python bindings import socket, select s = socket.socket() - defaults to TCP/IP s.connect s.bind, s.listen, s.accept s.sendall, s.recv rl,wl,xl = select.select([s],[],[]) if s in rl:

Slide 59

Slide 59 text

CPython implementation socketmodule.c and selectmodule.c

Slide 60

Slide 60 text

CPython implementation socketmodule.c and selectmodule.c Extensive dependencies on POSIX and on C sockets API

Slide 61

Slide 61 text

CPython implementation socketmodule.c and selectmodule.c Extensive dependencies on POSIX and on C sockets API Would have to implement those APIs in C

Slide 62

Slide 62 text

CPython implementation socketmodule.c and selectmodule.c Extensive dependencies on POSIX and on C sockets API Would have to implement those APIs in C Handle C arguments, addresses, buffer management

Slide 63

Slide 63 text

CPython implementation socketmodule.c and selectmodule.c Extensive dependencies on POSIX and on C sockets API Would have to implement those APIs in C Handle C arguments, addresses, buffer management Would have to call EFI protocols from C

Slide 64

Slide 64 text

CPython implementation socketmodule.c and selectmodule.c Extensive dependencies on POSIX and on C sockets API Would have to implement those APIs in C Handle C arguments, addresses, buffer management Would have to call EFI protocols from C Or, have many callbacks from C to Python

Slide 65

Slide 65 text

BITS implementation C helper for safe asynchronous event handling Otherwise entirely Python Python makes all EFI protocol calls

Slide 66

Slide 66 text

Calling EFI from Python via ctypes

Slide 67

Slide 67 text

Behind the scenes efi.system_table is a data structure

Slide 68

Slide 68 text

Behind the scenes efi.system_table is a data structure efi.system_table.ConOut is a pointer to a protocol

Slide 69

Slide 69 text

Behind the scenes efi.system_table is a data structure efi.system_table.ConOut is a pointer to a protocol .contents dereferences a ctypes pointer

Slide 70

Slide 70 text

Behind the scenes efi.system_table is a data structure efi.system_table.ConOut is a pointer to a protocol .contents dereferences a ctypes pointer Most EFI calls expect a “this” pointer

Slide 71

Slide 71 text

Behind the scenes efi.system_table is a data structure efi.system_table.ConOut is a pointer to a protocol .contents dereferences a ctypes pointer Most EFI calls expect a “this” pointer ctypes converts "Hello world\r\n" to a Unicode string

Slide 72

Slide 72 text

Behind the scenes efi.system_table is a data structure efi.system_table.ConOut is a pointer to a protocol .contents dereferences a ctypes pointer Most EFI calls expect a “this” pointer ctypes converts "Hello world\r\n" to a Unicode string ctypes returns the error code from EFI

Slide 73

Slide 73 text

Resource management EFI uses manual memory management

Slide 74

Slide 74 text

Resource management EFI uses manual memory management Python uses garbage collection

Slide 75

Slide 75 text

Resource management EFI uses manual memory management Python uses garbage collection Python GC doesn’t know about references from EFI

Slide 76

Slide 76 text

Resource management EFI uses manual memory management Python uses garbage collection Python GC doesn’t know about references from EFI Must keep Python object alive as long as EFI references it

Slide 77

Slide 77 text

Resource management EFI uses manual memory management Python uses garbage collection Python GC doesn’t know about references from EFI Must keep Python object alive as long as EFI references it Must explicitly free EFI resources when no longer referenced from Python

Slide 78

Slide 78 text

EFI networking protocols EFI_IP4_CONFIG2_PROTOCOL

Slide 79

Slide 79 text

EFI networking protocols EFI_IP4_CONFIG2_PROTOCOL Read current IP configuration, or start IP configuration

Slide 80

Slide 80 text

EFI networking protocols EFI_IP4_CONFIG2_PROTOCOL Read current IP configuration, or start IP configuration EFI_TCP4_SERVICE_BINDING_PROTOCOL

Slide 81

Slide 81 text

EFI networking protocols EFI_IP4_CONFIG2_PROTOCOL Read current IP configuration, or start IP configuration EFI_TCP4_SERVICE_BINDING_PROTOCOL Create a new EFI_TCP4_PROTOCOL, like socket()

Slide 82

Slide 82 text

EFI networking protocols EFI_IP4_CONFIG2_PROTOCOL Read current IP configuration, or start IP configuration EFI_TCP4_SERVICE_BINDING_PROTOCOL Create a new EFI_TCP4_PROTOCOL, like socket() EFI_TCP4_PROTOCOL

Slide 83

Slide 83 text

EFI networking protocols EFI_IP4_CONFIG2_PROTOCOL Read current IP configuration, or start IP configuration EFI_TCP4_SERVICE_BINDING_PROTOCOL Create a new EFI_TCP4_PROTOCOL, like socket() EFI_TCP4_PROTOCOL EFI socket API: Configure, Connect, Accept, Transmit, Receive, Close

Slide 84

Slide 84 text

EFI networking protocols EFI_IP4_CONFIG2_PROTOCOL Read current IP configuration, or start IP configuration EFI_TCP4_SERVICE_BINDING_PROTOCOL Create a new EFI_TCP4_PROTOCOL, like socket() EFI_TCP4_PROTOCOL EFI socket API: Configure, Connect, Accept, Transmit, Receive, Close

Slide 85

Slide 85 text

EFI networking protocols EFI_IP4_CONFIG2_PROTOCOL Read current IP configuration, or start IP configuration EFI_TCP4_SERVICE_BINDING_PROTOCOL Create a new EFI_TCP4_PROTOCOL, like socket() EFI_TCP4_PROTOCOL EFI socket API: Configure, Connect, Accept, Transmit, Receive, Close Glossing over quirks, bugs, error handling, workarounds, and compatibility with older versions

Slide 86

Slide 86 text

Impedance mismatch: select versus Receive/Accept select checks for pending data or connections

Slide 87

Slide 87 text

Impedance mismatch: select versus Receive/Accept select checks for pending data or connections Does not read data or accept connection

Slide 88

Slide 88 text

Impedance mismatch: select versus Receive/Accept select checks for pending data or connections Does not read data or accept connection EFI can only check for data by calling Receive with a valid buffer

Slide 89

Slide 89 text

Impedance mismatch: select versus Receive/Accept select checks for pending data or connections Does not read data or accept connection EFI can only check for data by calling Receive with a valid buffer Solution: buffer received data, call Receive when buffer empty

Slide 90

Slide 90 text

Impedance mismatch: select versus Receive/Accept select checks for pending data or connections Does not read data or accept connection EFI can only check for data by calling Receive with a valid buffer Solution: buffer received data, call Receive when buffer empty Likewise for Accept

Slide 91

Slide 91 text

Impedance mismatch: select versus Receive/Accept select checks for pending data or connections Does not read data or accept connection EFI can only check for data by calling Receive with a valid buffer Solution: buffer received data, call Receive when buffer empty Likewise for Accept Similar to the implementation of sockets in an OS kernel

Slide 92

Slide 92 text

Impedance mismatch: Poll EFI_TCP4_PROTOCOL not updated directly from low-level interrupts

Slide 93

Slide 93 text

Impedance mismatch: Poll EFI_TCP4_PROTOCOL not updated directly from low-level interrupts Data processed infrequently, even with asynchronous call running

Slide 94

Slide 94 text

Impedance mismatch: Poll EFI_TCP4_PROTOCOL not updated directly from low-level interrupts Data processed infrequently, even with asynchronous call running Caller expected to call Poll periodically if waiting

Slide 95

Slide 95 text

Impedance mismatch: Poll EFI_TCP4_PROTOCOL not updated directly from low-level interrupts Data processed infrequently, even with asynchronous call running Caller expected to call Poll periodically if waiting Improves performance by orders of magnitude

Slide 96

Slide 96 text

Impedance mismatch: Poll EFI_TCP4_PROTOCOL not updated directly from low-level interrupts Data processed infrequently, even with asynchronous call running Caller expected to call Poll periodically if waiting Improves performance by orders of magnitude Solution: call Poll inside helpers for select

Slide 97

Slide 97 text

Impedance mismatch: asynchronous callbacks All EFI socket calls asynchronous

Slide 98

Slide 98 text

Impedance mismatch: asynchronous callbacks All EFI socket calls asynchronous Calls take a “completion token” with EFI_EVENT to signal when done

Slide 99

Slide 99 text

Impedance mismatch: asynchronous callbacks All EFI socket calls asynchronous Calls take a “completion token” with EFI_EVENT to signal when done For sockets, EFI_EVENT must have a callback function

Slide 100

Slide 100 text

Impedance mismatch: asynchronous callbacks All EFI socket calls asynchronous Calls take a “completion token” with EFI_EVENT to signal when done For sockets, EFI_EVENT must have a callback function Need to handle callback safely from Python

Slide 101

Slide 101 text

Python concurrency model Python expects bytecode ops and C calls to run to completion

Slide 102

Slide 102 text

Python concurrency model Python expects bytecode ops and C calls to run to completion Global Interpreter Lock (GIL)

Slide 103

Slide 103 text

Python concurrency model Python expects bytecode ops and C calls to run to completion Global Interpreter Lock (GIL) Data may have inconsistent state when callback occurs

Slide 104

Slide 104 text

Python concurrency model Python expects bytecode ops and C calls to run to completion Global Interpreter Lock (GIL) Data may have inconsistent state when callback occurs Almost all CPython functions prohibited

Slide 105

Slide 105 text

Python concurrency model Python expects bytecode ops and C calls to run to completion Global Interpreter Lock (GIL) Data may have inconsistent state when callback occurs Almost all CPython functions prohibited Same problem arises with Ctrl-C and signals

Slide 106

Slide 106 text

Py_AddPendingCall Register a callback (with context)

Slide 107

Slide 107 text

Py_AddPendingCall Register a callback (with context) Python calls it at the next safe point

Slide 108

Slide 108 text

Py_AddPendingCall Register a callback (with context) Python calls it at the next safe point Can call arbitrary CPython functions from the callback

Slide 109

Slide 109 text

Handling events C module provides event callback function pointer

Slide 110

Slide 110 text

Handling events C module provides event callback function pointer Python code creates EFI_EVENT with C callback

Slide 111

Slide 111 text

Handling events C module provides event callback function pointer Python code creates EFI_EVENT with C callback C callback invokes universal Python callback

Slide 112

Slide 112 text

Handling events C module provides event callback function pointer Python code creates EFI_EVENT with C callback C callback invokes universal Python callback Python callback dispatches to event-specific callback via dict

Slide 113

Slide 113 text

Handling events C module provides event callback function pointer Python code creates EFI_EVENT with C callback C callback invokes universal Python callback Python callback dispatches to event-specific callback via dict dict keeps Python objects live while EFI_EVENT references them

Slide 114

Slide 114 text

Implementing select Takes read and write lists of sockets

Slide 115

Slide 115 text

Implementing select Takes read and write lists of sockets Or file descriptors; map to sockets via dict

Slide 116

Slide 116 text

Implementing select Takes read and write lists of sockets Or file descriptors; map to sockets via dict Loop over sockets until timeout expires

Slide 117

Slide 117 text

Implementing select Takes read and write lists of sockets Or file descriptors; map to sockets via dict Loop over sockets until timeout expires Call _read_ready or _write_ready

Slide 118

Slide 118 text

Implementing select Takes read and write lists of sockets Or file descriptors; map to sockets via dict Loop over sockets until timeout expires Call _read_ready or _write_ready _read_ready checks queue, calls Receive or Accept

Slide 119

Slide 119 text

Implementing select Takes read and write lists of sockets Or file descriptors; map to sockets via dict Loop over sockets until timeout expires Call _read_ready or _write_ready _read_ready checks queue, calls Receive or Accept If already running from previous call, call Poll

Slide 120

Slide 120 text

Implementing select Takes read and write lists of sockets Or file descriptors; map to sockets via dict Loop over sockets until timeout expires Call _read_ready or _write_ready _read_ready checks queue, calls Receive or Accept If already running from previous call, call Poll Handle connection closure to provide EOF from recv

Slide 121

Slide 121 text

Implementing select Takes read and write lists of sockets Or file descriptors; map to sockets via dict Loop over sockets until timeout expires Call _read_ready or _write_ready _read_ready checks queue, calls Receive or Accept If already running from previous call, call Poll Handle connection closure to provide EOF from recv Queues data or error when callback called

Slide 122

Slide 122 text

Implementing select Takes read and write lists of sockets Or file descriptors; map to sockets via dict Loop over sockets until timeout expires Call _read_ready or _write_ready _read_ready checks queue, calls Receive or Accept If already running from previous call, call Poll Handle connection closure to provide EOF from recv Queues data or error when callback called _write_ready returns true if connected

Slide 123

Slide 123 text

Implementing select Takes read and write lists of sockets Or file descriptors; map to sockets via dict Loop over sockets until timeout expires Call _read_ready or _write_ready _read_ready checks queue, calls Receive or Accept If already running from previous call, call Poll Handle connection closure to provide EOF from recv Queues data or error when callback called _write_ready returns true if connected Always calls Poll if connected

Slide 124

Slide 124 text

class socket __init__: Create EFI_TCP4_PROTOCOL from binding protocol

Slide 125

Slide 125 text

class socket __init__: Create EFI_TCP4_PROTOCOL from binding protocol __del__/close: Cancel all outstanding callbacks

Slide 126

Slide 126 text

class socket __init__: Create EFI_TCP4_PROTOCOL from binding protocol __del__/close: Cancel all outstanding callbacks connect: Call Configure and Connect

Slide 127

Slide 127 text

class socket __init__: Create EFI_TCP4_PROTOCOL from binding protocol __del__/close: Cancel all outstanding callbacks connect: Call Configure and Connect recv: Return data from queue

Slide 128

Slide 128 text

class socket __init__: Create EFI_TCP4_PROTOCOL from binding protocol __del__/close: Cancel all outstanding callbacks connect: Call Configure and Connect recv: Return data from queue Spin on _read_ready if queue empty; this starts a Receive

Slide 129

Slide 129 text

class socket __init__: Create EFI_TCP4_PROTOCOL from binding protocol __del__/close: Cancel all outstanding callbacks connect: Call Configure and Connect recv: Return data from queue Spin on _read_ready if queue empty; this starts a Receive sendall: Call Transmit; save status for

Slide 130

Slide 130 text

class socket __init__: Create EFI_TCP4_PROTOCOL from binding protocol __del__/close: Cancel all outstanding callbacks connect: Call Configure and Connect recv: Return data from queue Spin on _read_ready if queue empty; this starts a Receive sendall: Call Transmit; save status for bind: Save provided address and port for later calls

Slide 131

Slide 131 text

class socket __init__: Create EFI_TCP4_PROTOCOL from binding protocol __del__/close: Cancel all outstanding callbacks connect: Call Configure and Connect recv: Return data from queue Spin on _read_ready if queue empty; this starts a Receive sendall: Call Transmit; save status for bind: Save provided address and port for later calls listen: Call Configure for listening socket

Slide 132

Slide 132 text

class socket __init__: Create EFI_TCP4_PROTOCOL from binding protocol __del__/close: Cancel all outstanding callbacks connect: Call Configure and Connect recv: Return data from queue Spin on _read_ready if queue empty; this starts a Receive sendall: Call Transmit; save status for bind: Save provided address and port for later calls listen: Call Configure for listening socket accept: Return queued connection if any

Slide 133

Slide 133 text

class socket __init__: Create EFI_TCP4_PROTOCOL from binding protocol __del__/close: Cancel all outstanding callbacks connect: Call Configure and Connect recv: Return data from queue Spin on _read_ready if queue empty; this starts a Receive sendall: Call Transmit; save status for bind: Save provided address and port for later calls listen: Call Configure for listening socket accept: Return queued connection if any Spin on _read_ready if queue empty; this starts an Accept

Slide 134

Slide 134 text

Socket demo and walkthrough

Slide 135

Slide 135 text

High-level client demo

Slide 136

Slide 136 text

High-level server demo

Slide 137

Slide 137 text

Try it out yourself BITS: https://biosbits.org/

Slide 138

Slide 138 text

Try it out yourself BITS: https://biosbits.org/ QEMU/KVM

Slide 139

Slide 139 text

Try it out yourself BITS: https://biosbits.org/ QEMU/KVM Client works automatically

Slide 140

Slide 140 text

Try it out yourself BITS: https://biosbits.org/ QEMU/KVM Client works automatically For server, use hostfwd option to forward ports inside

Slide 141

Slide 141 text

Try it out yourself BITS: https://biosbits.org/ QEMU/KVM Client works automatically For server, use hostfwd option to forward ports inside OVMF: Open Virtual Machine Firmware, EFI for QEMU

Slide 142

Slide 142 text

Try it out yourself BITS: https://biosbits.org/ QEMU/KVM Client works automatically For server, use hostfwd option to forward ports inside OVMF: Open Virtual Machine Firmware, EFI for QEMU Or try it on physical hardware

Slide 143

Slide 143 text

Try it out yourself BITS: https://biosbits.org/ QEMU/KVM Client works automatically For server, use hostfwd option to forward ports inside OVMF: Open Virtual Machine Firmware, EFI for QEMU Or try it on physical hardware Check BIOS settings to enable EFI network stack

Slide 144

Slide 144 text

Try it out yourself BITS: https://biosbits.org/ QEMU/KVM Client works automatically For server, use hostfwd option to forward ports inside OVMF: Open Virtual Machine Firmware, EFI for QEMU Or try it on physical hardware Check BIOS settings to enable EFI network stack Use wired Ethernet

Slide 145

Slide 145 text

BIOS Implementation Test Suite (BITS) http://biosbits.org/ Questions?

Slide 146

Slide 146 text

Networking without an OS Demo Backup Josh Triplett [email protected] PyCon 2016

Slide 147

Slide 147 text

No content

Slide 148

Slide 148 text

No content

Slide 149

Slide 149 text

No content

Slide 150

Slide 150 text

No content

Slide 151

Slide 151 text

No content

Slide 152

Slide 152 text

No content

Slide 153

Slide 153 text

No content

Slide 154

Slide 154 text

No content

Slide 155

Slide 155 text

No content

Slide 156

Slide 156 text

No content

Slide 157

Slide 157 text

No content

Slide 158

Slide 158 text

No content

Slide 159

Slide 159 text

No content

Slide 160

Slide 160 text

No content

Slide 161

Slide 161 text

No content

Slide 162

Slide 162 text

No content

Slide 163

Slide 163 text

No content

Slide 164

Slide 164 text

No content

Slide 165

Slide 165 text

No content

Slide 166

Slide 166 text

No content

Slide 167

Slide 167 text

No content

Slide 168

Slide 168 text

No content

Slide 169

Slide 169 text

No content

Slide 170

Slide 170 text

No content

Slide 171

Slide 171 text

No content

Slide 172

Slide 172 text

No content

Slide 173

Slide 173 text

No content

Slide 174

Slide 174 text

No content

Slide 175

Slide 175 text

No content

Slide 176

Slide 176 text

No content

Slide 177

Slide 177 text

No content

Slide 178

Slide 178 text

No content

Slide 179

Slide 179 text

No content

Slide 180

Slide 180 text

No content

Slide 181

Slide 181 text

No content

Slide 182

Slide 182 text

No content

Slide 183

Slide 183 text

No content

Slide 184

Slide 184 text

No content

Slide 185

Slide 185 text

No content